Range finding, horizontal angle measuring, and angle of site instrument



J. T. ZAK

Aug. 24, 1937.

RANGE FINDING, HORIZONTAL ANGLE MEASURING AND ANGLE OF SITE INSTRUMENTOriginal Filed Dec. 11, 1934 HTTORNEY Patented Aug. 24, 1937 UNITEDSTATES PATENT OFFICE RANGE FINDING,

MEASURING, AND STRUMENT HORIZONTAL ANGLE ANGLE OF SITE IN- Joseph T.Zak, San Francisco, Calif.

Original application December 11, 1934, Serial No. 756,992. Divided andthis application July 15,

1936, Serial No. 90,703

4 Claims.

This invention described herein may be manufactured and used. by or forthe Government for governmental purposes, without the payment to me ofany royalty thereon.

This invention relates toan improved instrument of the type describedand claimed in my pending application Serial No. 756,992, filed December11, 1934, entitled Range finding, horizontal angle measuring, and angleof site instrument,

of which this application is a division; more especially it is directedto a simplified field instrument susceptible of use as a range finding,horizontal angle and angle of site measuring device.

One of the objects of this invention is to provide a simplified form ofrange finding, horizontal angle measuring and angle of site instrumentwhich may be constructed of any suitable available material such as astring, buttons and a pencil or the like and which is especially adaptedto be adjusted easily and quickly to an operative condition fordetermining accurate data for use in gunnery. 7

Another object of my invention is to provide a combined range finding,horizontal angle measuring and angle of site instrument in a unitarystructure, which is simple in construction, light in weight, efiicientin use and which is not liable to get out of order.

I-Ieretofore the instruments used in solving problems in gunnery ascompared to my invention were relatively bulky in construction andcomplicated in operation thereby causing the observer to waste time inmoving the instrument to position for operation and adjusting theinstrument before it was in condition for operation.

It is therefore the purpose of my invention to provide an instrumentwhich is compact in construction and simple in operation, there-bypermitting it to be immediately accessible under the conditions of fieldservice, and quickly adjusted to an operative condition.

With the above and other objects in view the invention consists infeatures of construction, ar-

rangement and operation of parts which will hereinafter appear. Forpurposes of illustration the invention will be described and claimedwith reference to the accompanying drawing in which like numbersdistinguish like parts and in which- Fig. 1 is a perspective view of. myinvention showing the manner in which the instrumentis used indetermining ranges;

Fig. 2 is a top plan view of the instrument;

Fig. 3 is a perspective viewof an eyepiece used in carrying out myinvention, with parts connected thereto broken away;

Fig. 4 is a diagrammatic view illustrating the manner of solving a rangeproblem with the instrument;

Fig. 5 is an enlarged side view partly in section illustrating theinstrument as assembled when not in use;

Fig. 6 is atop plan View of a modified form of side portion of theinstrument and Fig. 7 is a perspective View showing the manner in whichthe instrument is used in determining angles of site.

In the illustrated embodiment characterizing my invention, (I) indicatesa flexible member such as a string of predetermined length havingholding means (2) in the form of buttons or the like and an eye-piece(3) connected thereto at suitably spaced points thereon, whereby sideportions A, B and C are provided on the instrument.

The eye-piece (3) preferably comprises a rigid member, such as [a barwhich is provided with. a peep-slot (4) in its outer edge and havingsuitable fastening means such as hook like members (5) secured theretoto which the ends of the string (I) are connected detachably when usingthe instrument for the determination of ranges and horizontal anglemeasuring.

In'order to determine angles of site the eyepiece 3) is provided with afront sight comprising a mirror (8), on which is inscribed a horizontalreference line ('I). From adjacent the inner end of the reference line(1) on the other side edge of the eye-piece as zero, a plus mil scale(8) is inscribed on the upper portion of the front sight and-a minus milscale (5)) is inscribed on the lower portion.

The section 0 of the string (I) between the holding means (2) isprovided with marks to indicate a range scale (I0) a range correctorscale (I I) and an infinity mark (I2), the values of the range scale(I0) and corrector scale (II) being memorized by the observer. Similarmarks may also be provided on the section C of the string to indicate amil scale for measuring horizontal angles using a mark for each 50 mils.A suitable marker I3) such as a lead pencil eraser having a centralaiming mark (l4) provided thereon, is mounted slidably on the section 0of the string.

If desired a rigid member (I5) as illustrated in Figure 6 of thedrawing, may be substituted for sectioniC of the instrument. Inscribedon one end of the rigid member (15) is a range scale (I6), and aninfinity mark (ll) and on the other end ofthe rigid member is a rangecorrector scale ing, to his head by elastic straps (2|) with thepeep-slot (4) provided therein in line with the 1O aiming eye. Theobserver then holds section C of the instrument outwardly in extendedposition along the line of vision by means of the members (2) wherebythe instrument assumes a substantially equilateral triangular shape whenin opera- .15 tive position.

Reference being had to Fig. 4 of the drawing, the observer at extendsthe device as shown in Fig. 1, and places the infinity mark (l2) in linewith the target and glancing toward'the'range corrector'scale (I I),selects a convenient and 'distant reference object such as a tree andnotes the point on the range corrector scale (II) where the referenceobject intercepts said range corrector scale. The observer then lowersthe device and with the right hand slides the marker (I3) so that theaiming mark (I4) coincides with the point on rangecorrectorscale (I l atwhich the reference object was found to intercept said range correctorscale (II). The device is again extended as shown in Fig; 1 so that theinfinity mark (I2) is in line with the target and glances over aimingline (H) on marker (l3) to check up, verify and assure himself that theaiming line [4 is in line with the reference object. At 0 the 3 observerextends the device as in Fig. 1 so that scale (H3) to see where thetarget intercepts the.

range scale, which is the range as read, to be corrected by thesubtraction of the indicated per cent of correction as noted by theposition of the marker (l3) on the range corrector scale (I I).

To determine angles of site of a given object, the eye-piece (3) isremoved from the. flexible member or string (1) and a cross bar in theform of a' pin (22) is fitted in an aperture (23) provided in the upperendof the eye-piece, the ends of the pin extending outwardly an equaldistance from the side edges of the eye-piece as illustrated in Fig. 7of the drawing. The pin (22) provides means for suspending the eye-piecetherefrom, the eye-piece being adapted to swing freely on the pin, andalso provides means to which the ends of the string (I) may besuitablyconnected. The observer holds the pin (22) in one hand with theeye-piece extending downwardly therefrom and. held in a suspendedvertical position by means of gravity, the front sight of the eye-piecefacing the observer, he then holds the members (2) together against hisaiming eye with his other hand and sights on a target with the section Cof the string (I) extending downwardly therefrom. When the reflection ofthe pupil of the eye'in thernirror (6) is on line with the-zero in myprior Patent No. 1,723,456. a r h In assembling the instrument when notinuse" the string (I)- after having been disconnected from the ends ofthe pin.(22) is wrapped around the eye-piece and the pin isremoved-fromthe g aperture (23) and inserted in a longitudinal extending slot (24)provided in the lower portion of the eye-piece where it is held in placeby means of a suitable catch (25),.as illustrated in Fig. 5 of thedrawing.

The range scale used on the instrument is based on the followingformula:R M equals 1,000 W, where R is a range, M the angular width inmils of the target or base line and W the lineal Width of the target orbase line. case the range scale is selected for a base line of 50-yards,where the base line and reference object are at right angles to theobserver target line and the portion C of the string is held at acomputed distance from the eye of the observer. Inasmuch as thedirection of the base line will vary with the position of the referenceobject (the object which determines the direction of base line) theactual W of the formula will become less as the angletarget-observerreference object becomes less and the actual rangereading will be correspondingly greater than the In the present ing mustbe balanced." In extremely long ranges i the baseline can be doubledfor'accuracy, hence the final range reading must be doubled to securecorrect range. 'It is possible to'accurately take the range to a targetseveral thousand yards distant provided the'base lineis correspondinglyincreased. V a

The above disclosed instrument can be used in a sitting, kneeling,standing or prone position.

It has been found in using the instrument that i the position forobtaining the greatest steadiness thereof is in the sitting positionwith the elbows resting on the knees and the breath held as in firing arifle. When using the instrument in the prone position the observer'lieson his back, feet towards the target and head raised above the breast.For measuring the base line a five or ten yard length of any suitablewire, such as picture wire, may be used. A good string givessatisfactory'results. Careful pacing of base line eliminates the need ofa string. V It will thus be seen that I have provided a highly novel andsimple form of a combinedrange finding, horizontal angle measuring andangle of site instrument, which is well adapted for all the purposesdesignated. Even thoughI have herein describedmy invention as comprisingcertain details of construction and operation, it is nevertheless to beunderstood that Various changes may be made therein without departingintervals, there being a range scale, range corrector scale, a scalegraduated in mils, an infinity mark, and a movable marker on saidflexible member intermediate said holding means;

j 2. An instrument of the character described, "comprising a flexiblemember of predetermined length, 'a trio of members connected thereto atequally spaced points thereon, providing sideportions, one of said trioof members'comprising an eye-piece adapted to be secured to the head of-the user of the instrument in front of his aiming eye, and the other ofsaid members providing means for holding one of said side portions inextended position along the line of vision of the observer, there beinga range scale, corrector scale, mil scale, an infinity mark and amovable marker on said last mentioned side portion.

3. An instrument of the character described, comprising a flexiblemember of predetermined length, a trio of members connected thereto, atequally spaced points thereon, two of said trio of members comprisingholding means and the other thereof comprising an eye-piece, a rangescale, corrector scale, infinity mark, mil rule scale and a movablemarker provided on said flexible member intermediate said holding means,said eye-piece comprising a bar containing an eyeslot and means fordetermining angles of site.

4. An instrument of the character described, comprising a flexiblemember of predetermined length, a trio of members connected thereto, atsuitably spaced points thereon, two of said trio of spaced memberscomprising holding means and the other thereof comprising an eye-piece,a range scale, range Corrector scale, infinity mark, mil rule scale anda movable marker provided on said flexible member intermediate saidholding means, said eye-piece comprising a bar containing an eye-slotand means for determining angles of site, said' means comprising a plusand minus angle of site scale inscribed on said bar, and a reflectingsurface bearing a reference at the zero of said scale.

JOSEPH T. ZAK.

